Why Airplanes Have All Those Tiny Holes In The Windows
By C. Gordon
VACATIONS
The tiny little hole at the bottom of an airplane window is perfectly normal. It's actually making the flight a bit safer by helping to regulate the pressure around the windows.
Known as a bleed hole, its role is to help ease the pressure on the windows as the plane gains altitude, especially in the case of an emergency with rapid changes in pressure.
The windows are, in essence, one of the weakest spots on the plane's fuselage, so they are designed to withstand extreme conditions, and that little hole is part of it.
Since the air pressure inside the cabin is regulated, the bleed hole located on the middle pane helps regulate the pressure between the outer and inner window layers.